Differential roles for ETS, CREB, and EGR binding sites in mediating VEGF receptor 1 expression in vivo

Abstract

Vascular endothelial growth factor receptor 1 (VEGFR1) is a marker for endothelialspecific gene expression. We previously reported that the human VEGFR1 promoter (between -748 and +284) contains information for expression in the intact endothelium of transgenic mice. The objective of this study was to dissect the cis-regulatory elements underlying VEGFR1 promoter activity in vitro and in vivo. In primary endothelial cells, binding sites for E74-like factor 1 (ELF-1; between -49 and +52), cyclic adenosine monophosphate response element binding (CREB; between -74 and +81), and early growth response factor 1/3 (EGR-1/3; between -16 to +25) were shown to play a positive role in gene transcription, whereas a putative E26 transformation-specific sequence (ETS) motif between -36 and +39 had a net negative effect on promoter activity. When targeted to the Hprt locus of mice, mutations of the ELF-1 binding site and the CRE element reduced promoter activity in the embryonic vasculature and resulted in a virtual loss of expression in adult endothelium. Postnatally, the EGR binding site mutant displayed significantly reduced promoter activity in a subset of vascular beds. In contrast, mutation of the -39 ETS site resulted in increased LacZ staining in multiple vascular beds. Together, these results provide new insights into the transcriptional regulatory mechanisms of VEGFR1. © 2009 by The American Society of Hematology.